It’s soft which makes It low energy
Answer:
D H2PO4– + HPO42–
Explanation:
The acid dissociation constant for 
are 
respectively.
The reason while option D is the best answer is that, the value of pKa for both
lies on either side of the desired pH of the buffer. This implies that one is slightly over and the other is slightly under.
Using Henderson-Hasselbach equation:
Because mass is not always the same for objects made from the same material. Just because an object has the same mass as another doesn’t mean they are the same material.
1 mol of any gas or mix of gases at STP conditions will have a volume of 22.4 L. Since the problem doesn’t said what are the conditions I will asume that are STP condition and the volume of one mole of the mix will have a volume of 22.4 L.
You may know that density is
D=m/v
In one mole of air I will have 80% of Nitrogen (N2) and 20% oxygen (O2).
So the mass of one mole of air will be
14 x2x0.80+16x2x0.20 = 22.4 g + 6.4 g = 28.8 g
D= 28.8/22.4 = 1.28 g/L
Of course if the temperature is higher the density will be smaller because the volume of one mole will be bigger and viceversa if the temperature decrease. Also if the pressure is different than one atm the volume of a mol will change.
